Meningitis

Meningitis is a serious infection of the meninges, the membranes covering the brain and spinal cord. It is a devastating disease and remains a major public health challenge. The disease can be caused by many different pathogens including bacteria, fungi or viruses, but the highest global burden is seen with bacterial meningitis.

There are four main causes of acute bacterial meningitis: meningococcus, pneumococcus, Haemophilus influenzae and Streptococcus agalactiae, also known as Group B streptococcus (GBS). Meningococcus has the most potential to produce outbreaks and large-scale epidemics. The largest burden of meningococcal meningitis occurs in the meningitis belt, an area of sub-Saharan Africa, which stretches from Senegal in the west to Ethiopia in the east.

Meningococcal meningitis can affect anyone of any age. Overall, mortality is highest in children younger than 5 years. The route of transmission varies by organism. Most bacteria that cause meningitis are carried in the human nose and throat. They spread from person to person by respiratory droplets or throat secretions. GBS is often carried in the human gut or vagina and can spread from mother to child around the time of birth. Carriage of these organisms is usually harmless and helps build up immunity against infection, but the bacteria occasionally invade the body causing meningitis and sepsis.

The symptoms of meningitis can differ based on the cause, how quickly the disease progresses, how long it lasts, brain involvement, and other serious complications like sepsis. Less frequent symptoms include seizures, coma, and neurological deficits, such as weakness of the limbs. Infants often have different symptoms compared to adults, such as unusual behaviour; irritability; weak, continuous cry; poor feeding, and bulging of the soft spot in their head.

Some bacterial pathogens may also account for other symptoms as a result of bloodstream infection, which can quickly lead to sepsis, including cold hands and feet, fast breathing, and low blood pressure. A characteristic, non-blanching skin rash may appear with meningococcal sepsis.

Meningitis is a medical emergency and requires urgent medical attention. Antibiotic treatment should be started as soon as possible when bacterial meningitis is suspected. The first dose of antibiotic treatment should not be delayed until the results of the lumbar puncture are available. In non-epidemic settings, intravenous corticosteroids are initiated with the first dose of antibiotics, in order to reduce the inflammatory response and the risk of neurological sequelae and death.

If treatment is started prior to the lumbar puncture, it may be difficult to grow the bacteria from the spinal fluid and confirm the diagnosis. However, confirmation of the diagnosis should not delay treatment.

Vaccines against meningococcal, pneumococcal and Haemophilus influenzae disease have been available for many years. These bacteria have several different strains and vaccines are designed to protect against the most harmful ones. No universal vaccine exists. Vaccines against GBS are in development.

Intravenous penicillin can be administered to mothers at risk of transmitting GBS to their babies during labour, to prevent their babies developing GBS infection. Post-exposure prophylaxis with antibiotics is given to close contacts of individuals with meningococcal disease to eradicate asymptomatic meningococcal carriage in the nose and decrease the risk of transmission.